Ill start...
Im level 21 now and loving the game! My name is nKD(Negative KD) Litego.
Heres my primary build, the one I like the most
Name: SMG
Primary Weapon: Feline, Reflex, Suppressor, Extended Mag.
Secondary Weapon: Hammer
Explosive: M 17 Frag Grenade
Suit Modules: Armor Enhance, Covert Ops, Mobility Enhance.
Tactic: Basically I just sprint all the time! My general rule still stands, never stand still! When I meet people I turn on Armor mode, aim for the head and start strafing, kill them, then I sprint off again. On Crash Site I always throw my grenade at the site before I approach it, almost always get at least 1 kill that way, its hilarious!
Im thinking of changing Reflex sight with Laser and Mobility Enhance with Point Fire Enhance so I dont have to aim down sight and can keep sprinting

Heres my secondary build:
Name: Sniper
Primary Weapon: DSG-1, Sniper, Suppressor, None (I will get Extended Mag on my next unlock).
Secondary Weapon: Feline, Laser, Suppressor, Extended Mag.
Explosive: M 17 Frag Grenade
Suit Modules: Proximity Alarm, Visor Enhance, Loadout Pro.
Tactic: Camp in a corner somewhere and shoot people in the head. When Im out looking for people I stealth, destealth, shoot, and back to stealth. After killing someone I move to a different place. While moving from one place to another I have my Feline up in case I meet someone.
I have more builds, but I almost never play them.